The present invention relates to the field of reclosable packages and an apparatus used to apply closure elements to a packaging film and form such packages. More particularly, the present invention relates to a method and apparatus for applying reclosable profile elements to a packaging film in a form, fill and seal packaging operation.
One method of forming packages is known as the form, fill and seal method, wherein a continuous length of film is fed forwardly and downwardly over a forming tube, with the marginal edges of the sheet of film being sealed to each other. The thus formed tube of film is cross-sealed, and contents are dropped into the packaging through the tubular mandrel over which the packaging film is formed. An additional cross seal above the contents completes the package, which is then severed from the tubular film.
Reclosable packages having male and female cooperating reclosable elements along an opening or seam of the package have been well known for some time. There are several advantages to forming product-containing packages with such reclosable fasteners. As such, several methods have been developed to produce packages with reclosable fasteners on form, fill and seal equipment.
U.S. Pat. No. 5,127,208 discloses a method and apparatus for forming a reclosable package in which a loop of the packaging film is created along the outside diameter of the fill tube. The reclosable profile element is guided along the exterior of the fill tube into the loop of packaging film and adhered to the inner surface of the loop. The method of the ""208 patent includes several inherent drawbacks which are addressed by the method of the present invention.
The present invention provides a method and apparatus for applying a reclosable fastener to a packaging film during the form, fill and seal formation of a package.
In one aspect of the invention, the packaging apparatus includes a guide block that is formed along the interior of the fill tube and extends down its length. The locking portion of the zipper is received within a shaped groove formed in the guide block. At the same time, a supply of packaging film is received around a forming collar and directed around the outer circumference of the fill tube.
The apparatus includes a knockdown plate spaced from the outer wall of the fill tube that folds the pair of flanges of the zipper down into contact with the outer wall of the fill tube. Each of the profiles of the zipper may or may not include a score mark to encourage the folding of the flange flat against the outer wall of the fill tube.
The packaging film passes over a rod extending parallel to the initial portion of the fill tube. The rod creates the header for the resealable package. Along the initial portion of the fill tube, a heated seal bar straddles the rod and moves into contact with the film and zipper to seal the film to each of the flanges of the zipper.
After the zipper has been attached to the packaging film, drive belts or drive wheels move the combination along the length of the fill tube. As the packaging material moves along the fill tube, the outer surface of the guide block begins to extend outward from the outer surface of the fill tube. At the lowermost portion of the fill tube, the guide block becomes a flat bar to aid in transitioning the package from a tubular member to a flat shape that can be side sealed to form each individual package.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.